<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8" />
		<title>3.姓名案例_watch实现</title>
		<!-- 引入Vue -->
		<script type="text/javascript" src="../js/vue.js"></script>
	</head>
	<body>
		<!-- 准备好一个容器-->
		<div id="demo">
			姓：<input type="text" v-model="firstName"> <br>
			名：<input type="text" v-model="lastName"> <br>
			姓名：<span>{{fullName}}</span>
		</div>
	</body>

	<script type="text/javascript">
		//阻止 vue 在启动时生成生产提示。
		Vue.config.productionTip = false
		
		new Vue({
			el:'#demo',
			data:{
				firstName:'zhang',
				lastName:'san',
				fullName:''
			},
			watch:{
				//监视firstName(姓)
				firstName:{
					immediate:true,
					handler(val){
						this.fullName = val + '-' + this.lastName
					}
				},
				//监视lastName(名)
				lastName(val){
					this.fullName =  this.firstName + '-' + val
				}
			}
		})
	</script>
</html>